API_project/Packaging_module/src/Case_package/case_demo4.java

package Case_package;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;
import java.util.Date;

public class case_demo4 {
    public static void main(String[] args) throws ParseException {
        //请使用代码实现计算你活了多少天，用JDK7和JDK8两种方式完成

        //JDK7
        //规则：只要对时间进行计算或者判断，都需要先获取当前时间的毫秒值

        //1、计算出生年月日的毫秒值
        String birthday = "2002年3月7日";
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日");
        Date date = sdf.parse(birthday);

        long birthdayTime = date.getTime();

        //2、获取当前时间的毫秒值
        long todayTime = System.currentTimeMillis();

        //3、计算间隔了多少天
        long time = todayTime - birthdayTime;
        System.out.println(time / 1000 / 60 / 60 / 24);


        //JDK8
        LocalDate ld1 = LocalDate.of(2002, 3, 7);
        LocalDate ld2 = LocalDate.now();

        long days = ChronoUnit.DAYS.between(ld1, ld2);
        System.out.println(days);

    }
}